Imagine walking down the street just as the crew of an airplane flying overhead decides to dump sewage from the plane's toilets. Not a pleasant thought. Fortunately, airlines aren't allowed to do this.

But cruise ships do it all the time — and not just with sewage, but with food waste, oily bilge water, and solid waste as well. As an article on the nonprofit news website DC Bureau notes, cruise ship companies that rely on "pristine oceans, beautiful coral reefs and marine life" and "that advertise excursions to untouched ocean scenery are threatening these very same natural resources with their standard practice of flushing harmful toxins, mostly as sewage and food waste, into the ocean."

Although some cruise ship companies have made improvements in waste-water treatment, the industry still has a long way to go. And even though sewage is subject to some regulations, food-waste dumping is not regulated. Considering that a cruise ship can serve from 10,000 to 25,000 meals a day, that's a lot of leftover scraps and waste that are ground up and dumped into often-fragile ocean ecosystems. This waste becomes acidic as it decomposes, increasing nutrients that starve the ocean of oxygen and contribute to the creation of dead zones. Read more...